They literally don’t. That’s false.
At worst, they gave money to a group who (after Chik fil A stopped giving them money) gave money to a preacher who went to Uganda around the time they were writing a death-penalty-for-homosexuality bill. The preacher, a nutjob, commended Uganda for being anti-gay and condemned the bill for having too harsh a penalty.
He had nothing to do with the writing of the bill and frankly had little to do with Chik Fil A. Also, the bill did not pass with the kill-the-gays portion; Uganda does not execute people for being gay. They do throw them in prison, which is not much better, but what you said is a lie.
To spin this story into “Chik Fil A gives money to a regime that executes gay people” requires falsehoods at every juncture.
https://www.snopes.com/fact-check/uganda-murder-gay-chick-fil-a/